Hey guys, I haven't posted in a while, but I'm stumped.

I have an 03 ES300 and about two months ago I had the 120K mile service at the dealer (spark plugs, air filter, oil change, transmission service, brakes, induction cleaner...) I also replaced my Michelin Energy tires with 4 new Michelin Primacy tires the day before.

Ever since I bought the tires and had the service my fuel economy has sucked.

I went from around 25.5-26MPG to around 21MPG

So, do you think my mileage drop has to do with the tune up or the tires or something else...

Thanks for the help

 

Did you gap the plugs before you installed them?

 

bring it back and have them recheck everything.

 

I let the dealer do the plugs ( Transverse Engines are a PIA LOL)

 

Thanks, I think that's what I will do.

 

Are the tires properly inflated?

 

Check your tire pressure I have had the dealer put in the total wrong pressure and I was getting way less Miles Per Gallon

 

Did you ever change your plug wires? They could have broken or the contact become loose when they changed the plugs. Tires, unless greatly underinflated, would affect gas mileage but not that much unless they were almost flat.

 

A change in driving routs can also affect gas mileage. Did you change jobs? School? Girlfriend?

 

Mis gapped plugs will do it everytime, and low tire pressure

 

What is the plug gap supposed to be?

I guess I could take the front plugs out and see if they are gapped correctly and assume the rear ones are the same.

 

I'd love to know the specs on the tires, let me know the sizes for the ones you have and the ones you replaced, there may be a weight difference there that could account for PART of the issue.

In addition, if the battery was unplugged at any time (highly likely when doing the tuneup), these Lexus vehicles have what I like to call an adaptive transmission. It senses how you drive. Floor it around town and the MPG will drop. Most of this is done, from my experience, with the first 100 miles or so you drive around after reconnecting the battery. That's why I take it very slow and don't even floor it (not even once) so as to protect my MPG. I don't race anymore so I don't need the power. Thus, driving habits can also cause issues.

Yes, check the tire pressures...I agree.

Also, do we know what oil was in there and what it was replaced with?

 

Thanks for all the help so far. To answer a few of your questions, the tires are the stock size on stock 16" rims same size as the old ones that I replaced. The old tires were Michelin Energy MXV4 the new ones are Michelin Primacy. The tire pressure is 30 psi all around. I drive the same route/ style as before, and use premium Shell gasoline.

I did not think about the ECU being reset- think I may need to reset it again and drive like an egg is under the accel for a few hundred miles?

What about a vacuum leak?

 

The tire size is: 215/60/16

 

Bring the tire pressure to 35 lbs. Carl